The RadListBox control as any other selector control is not designed to support built-in inline editing of the items. The mentioned inline editing is not available in the default ListBox control which is why it has not been consider to be implemented as a built-in feature in the RadListBox control.
Currently we do not have an example that we can share with you that shows how the described scenario could be achieved. You can take a look at this post which describes a possible approach of achieving the desired behavior:
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